Valuable chemicals, such as aminoalcohols, are often produced in equipment that operates at high temperature and pressure utilizing catalysts and reactive gasses, such as hydrogen. A critical part of the manufacturing process involves separating the valuable product from the catalyst and the high pressure gas. It is common practice to vent the reactors to relieve the pressure and to filter the catalyst to separate it from the product. Due to the hazards frequently associated with handling the gas and/or the catalyst it is desirable to minimize this handling. Additionally, it is desirable to avoid venting the gas due to the lost material and time that this step incurs. It is also desirable to minimize filtration of the catalyst since this also may be time consuming and costly and somewhat hazardous.
Catalytic hydrogenations over heterogeneous catalysts may be carried out using fixed bed reactors in order to obtain the advantages of a continuous process. For various reactions, fixed bed reactors are, however, unsuitable, since, to achieve complete conversion in a single pass, such reactors would to have to be very large. Additionally, the amount of heat that comes from the hydrogenation of certain compounds can cause problems with regard to heat removal, such as loss of selectivity in the reactor. To reduce the amount of heat, partial conversion and recycle may be used; however, partial conversion may not be appropriate because the selectivity and yield of reaction are adversely affected. Other processes use a bubble column reactor; however, a second (finishing) reactor is often used to provide more complete conversion.
Desirable catalysts for the production of aminoalcohols include unsupported base-metal catalysts such as nickel or cobalt, often in their sponge form. The properties of these catalysts makes filtration significantly more difficult in comparison to supported metal catalysts. A need exists, therefore, for a system that enables the valuable product to be removed continuously from a hydrogenation reactor operating at elevated pressure while simultaneously maintaining the gas pressure and retaining the valuable catalyst inside of the reactor system.